There are 2 issues that appear to be going on here....

The 1st issue - Remaining Estimates (Create an Issue)

When I create a new or edit an Issue, and I try to set the Remaining Estimates to "Leave Estimates Unset", the radio button for Leave Estimates Unset is chosen. However when I go to log work, I am getting an error that states 'Remaining Estimates is Invalid".

If I go back into the edit mode of the Issue to see if my setup is still set on Leave Estimates Unset, I see that is has changed to Adjust automatically. It is not saving my choice selection.

The 2nd issue - Log Work

When I choose the Log Work and I make my entries into the pop-up box, if I put "0" in the Remaining Estimates field, they system auto changes that entry to display "N/A".

However, if I delete the N/A and reenter the "0" again, they system takes that entry and I am able to log work. Is this a current bug issue or does this currently work this way?
This appears as a bug with a workaround to remove the N/A and enter the "0" or whatever value to be able to proceed further.

This does not matter is I config my screen to display the log time fields when a user creates an Issue or not